This invention relates to cosmetic and/or pharmaceutical arts. More specifically, the invention relates to a composition containing as an active ingredient an extract of a plant belonging to the family Labiatae, for enhancing hyaluronic acid productivity in a mammal, particularly tissue or cell of a human. The invention also relates to a composition for topical application to mammalian skin containing as an active ingredient an extract which is an extract of a plant belonging to the family Labiatae and first used for such a composition.
As substances having an activity to accelerate the synthesis or production of hyaluronic acid in certain cell culture tests on mammals, there have been known an extract of Ulva pertusa, a marine plant generally classified as a lower plant (Japanese Laid-open Patent Publication No. 9422/1994), extracts of other marine plants; for example, plants belonging to the family Ulvaceae, Gracilaria or Gelidium (Japanese Laid-open Patent Publication No. 101871/1995). Further, it is suggested that, due to the hyaluronic acid synthesis acceleration activity, these extracts bring about the activation of dermal cells, etc.
The existence of some relation between such hyaluronic acid synthesis acceleration ability and the activation of dermal cells may be accepted from the following actual situation or findings. Namely, hyaluronic acid is widely distributed in living bodies, e.g. in skin, articular liquid, corpus vitreum, ligamenta, etc., and, for example in skin, plays important roles such as the adhesion of the cells, the protection of the cells, the formation of dermal tissues, the retention of histionic water and the maintenance of flexibility. Further, in degenerative joint disease and rheumatism, hyaluronic acid generally lessens their effect and there fore injections containing hyaluronic acid itself as an active ingredient are used, and in operations of cataracta, hyaluronic acid is used as an auxiliary for the retention of aqueous chambers.
On the other hand, as symptoms of dermal aging, there can be mentioned "lowering of wetness" and "lowering of tenseness", and occurrence of "wrinkles", "flabbiness" and the like following them. Causes of these phenomena have not yet been solved completely, but as reported in Biochemica Biophysica Acta, 279: 265 (1972); Japanese Journal of Society for Cosmetic Chemists, 15: 77 (1981); Cell Structure and Function, 9: 357 (1984); Carbohydrate Research, 159: 127 (1987), etc., it is considered that dermal functions are influenced by the lowering of water content of the skin partly due to the decrease of hyaluronic acid production by dermal cells in proportion to aging.
When such actual situation or findings are taken into consideration, even if application to skin is a main object, it is desired to provide substances which are high in safety, and act directly on dermal cells and accelerate the production of hyaluronic acid in the dermal tissue more strongly. Thus, the object of the invention lies in providing substances which are superior to usual plant extracts in activity to enhance hyaluronic acid productivity in tisse or cells including human skin, and use thereof.